US3269320A - Pump control method and apparatus - Google Patents

Description

Aug. 30, 1956 A, ET AL 3,269,320

PUMP CONTROL METHOD AND APPARATUS Filed June 16, 1964 5 Sheets-Sheet 1 POWER 2 SOURCE CONTROLLER INVENTORS AUBRA E. T/LLEV OKE A. FREQR/KSSON TROY J. PEMBERTOIV Aug. 30, 1966 A. E. TlLLEY ET AL PUMP CONTROL METHOD AND APPARATUS 5 Sheets-Sheet 2 Filed June 16, 1964 POUNDING NOISE| WAVE L ETS AMP.

GEOPHONE SENSITIVITY ADJUSTER DETECTO R MULTIVIBRATOR INTEGRATE TIME ADJUSTER R W W U P INVENTORS AUBRA E. T/LLEY Aug. 30, 1966 L ET AL 3,269,320

PUMP CONTROL METHOD AND APPARATUS Filed June 16, 1964 5 Sheets5heet 3 0 Z M A G 2 U U U 2 IOQ Ill

O O O 2 S 4 LL w INVENTORS I z AUBRA E. T/LLEV 0 *5 OKE A. FREDR/KSSON E [L may J. PEMBERTON 0 Z w o o o United States Patent 3,269,320 PUMP CONTROL METHOD AND APPARATUS Aubra E. Tiiley and Gite A. Fredrilssson, Fullerton, Calif., and Troy J. Pemherton, Stillwater, Okla, assignors to Chevron Research Company, a corporation of Delaware Filed .lune 16, 1964, Ser. No. 375,459 8 laims. (Cl. 1i)325) This invention relates to recovering oil from oil-producing formations, and more particularly this invention relates to a control system for controlling pumps used to lift oil from oil wells.

In the recovery of oil from wells it is common to use pumps to lift the oil from the well to the surface. In many wells, especially during the later stages of their exploitation, the quantity of oil entering the Well from the formation is often less than can be readily handled by the pump. When the pump runs continually under these conditions, the pump soon becomes pumped off. A reciprocating pump working partially filled will pound. That is, the pump piston at the top of its stroke is out of the liquid, and when the piston moves down the pump barrel, it strikes the upper level of the liquid. These impacts cause strong vibrations to be transmitted to the pumping apparatus.

One method of preventing pump pounding and the related vibration of course is to operate the pump only when there is enough liquid in the pump barrel so that pounding will not occur. Thus the pump is operated less than full time to insure that the liquid level in the Well Will remain high enough to completely fill the pump barrel and to thus prevent pounding. Theoretically then in a given well a pump might be operated, for example, for about one hour out of every six hours to always keep the well pumped off without objectional pounding occurring. Since there is no Way to predict with complete accuracy the pounding cycle of a given well, however, control of the pumps to prevent pounding has been a problem. It is also desirable from the standpoint of maximizing oil recovery from the well to have the pump operate as long as possible. In this regard it is actually desirable to have some pounding occur before shutting off the pump. Therefore the pump should be capable of operating as much as possible commensurate with the allowable tolerance of the pumping equipment to the pounding phenomena.

Heretofore a number of attempts have been made to control the operation of well pumps to prevent pump pounding. The control systems suggested heretofore have not coupled reliability of operation with ease of installation and therefore there is presently a need for a control unit which is reliable in sensing pounding and which then acts to shut oh the pump and to later restart the pump and which unit is also readily and easily installed on any type of well pump.

It is a particular object of the present invention to provide a control system adapted to sense the occurrence of pump pounding and to shut off the pump after the pounding has continued for a determinable length of time and which control system is readily installable on any existing well pump structure.

In one aspect, the present invention comprises means for sensing pounding of a well pump and means for transmitting the sensed pounding into an equivalent electrical voltage. The equivalent electrical voltage is amplified and detected by a detector means. The detector means provides a pulse only when the amplified input is above a predetermined threshold. The pulses from the detector means activate a multivibrator means which produces pulses of uniform height and controllable length. Each multivibrator pulse activates a switching means during the 3,269,326 Patented August 30, 1966 pulse time. After a predeterminable cumulative pulse time, the switching means acts to shut off the pump and at the same time activates a timing means. The timing means is preset to restart the pump after a predeterminable period has passed.

Further objects and advantages of the present invention will become apparent when the following detailed description is read in light of the accompanying drawings which are a part of this specification, and in which:

FIGURE 1 is a diagrammatic view illustrating apparatus assembled in accordance with present invention;

FIGURE 2 is a diagram schematically illustrating the preferred embodiment of apparatus of the present invention;

FIGURE 3 is a circuit diagram of the preferred embodiment of the present invention.

With reference now to FIGURE 1, a form of pumping apparatus is diagrammatically illustrated. As there shown, oil is being recovered from formation 20 through well 21 by means of pump 22 and tubing 23. The oil enters the well 21 through the slots 25 in casing 26. A pump indicated generally as 22 is located adjacent to producing formation 20 and is used to raise the oil to the surface. The operation of the pump is well known in the art and generally the oil enters the pump chamber through the port 28 below standing valve 29. A traveling valve 30 connected by appropriate means tosucker rod 31 utilizes reciprocating motion to move oil up the tubing 23 to the wellhead 24 and out fiowline 32.

The sucker rod 31 is reciprocated by means of a rocking arm 33. A horses head 34 is provided at one end of the rocking arm and is connected to the sucker rod 31 by a bridle 35. The rocker arm 32 is pivotally connected by suitable means, such as pin'36, to a Sampson post 37. The other end of the rocking arm 33 is driven by electric motor 38 through appropriate linkage 39 and 40.

The control system of the present invention includes means for sensing vibration. A preferred means for sensing vibration is a geophone 41. The geophone 41 is mounted on the pumping apparatus at a suitable place, such as on Sampson post 37. The geophone 41 senses vibrations caused by pump pounding and transmitted to the Sampson post through the sucker rods. The geophone 41 is electrically connected by suitable means to the controller 45 of the present invention. For example, wires 42 and 43 are useful to connect the geophone to the controller 45. A manual switch 27 may be provided if desired in the circuit. The power source 44 for the electrical motor 38 is connected through the controller 45.

When the liquid level in the pump barrel 22 is located above the upper level of the traveling valve 30 at the top of the pumping stroke, no pounding occurs. However, when the liquid level in the pump barrel is below the upper end of the traveling valves motion as illustrated by 46, then pounding occurs when the traveling valve 30 contacts the liquid on the downstroke of the pump. When the standing valve 23 strikes the liquid on the downstroke, the shock resulting from the impact is transmitted up the sucker rod 31 and through the pumping apparatus. The geophone 41 senses the shock and transmits a signal to the controller 45. This signal is detected in the controller 45. A similar shock occurs during each subsequent pumping cycle when the pump barrel is not full of liquid. After the geophone has sensed and the controller has detected a predeterminable number of pounds, the controller 45 causes the pump to stop by disconnecting the pump motor 45 from the power source 44. A timing means is provided in the controller 45 to automatically restart the pump after passage of a predeterminable time interval. The length of the time interval can be adjusted according to information obtained from the well during 3 testing to provide the optimum cycle of pump operation within the limits of acceptable pounding.

With reference now to FIGURE 2, the preferred embodiment of apparatus from the present invention will be more fully described. Assume for purposes of the description that the pump has been running for some time and that the liquid level in the pump barrel has dropped and pounding is just beginning to occur. The pounding causes vibration in the pumping apparatus. The vibrations are schematically illustrated in FIGURE 2 as pounding Wavelets 49. The geophone 41 picks up the vibration caused by the pounding and feeds an electrical voltage equivalent of the vibration to an amplifier means 50. The electrical voltage equivalent is represented by wavelets 51. The amplifier means 50 feeds the amplified sig nal into detector 52. The detector gives out a pulse only when the amplified input 51 is above its threshold. The pulses from the detector 52 activate multivibrator 54, which in turn produces pulses of uniform height and controllable length. These pulses are represented by Wave forms 53. Each multivibrator pulse 53 deactivates relay K While the relay K is deactuated it causes a clock motor 56 to turn a slotted wheel 57 at a constant rate. For example, a rate of one revolution per day, or per hour has been found satisfactory. A microswitch arm 58 having a finger 59 positioned in slot 60 closes the circuit to the pump power by keeping relay K energized and thus keeps the pump motor running and the pump working. During each pulse of the multivibrator the clock motor is activated and causes wheel 57 to turn a fraction of a degree. After accumulative multivibrator pulse length time the slot 60 will have traveled far enough to push the finger 59 of the microswitch arm 58 out of the slot 60 and up to the rim 61 of the Wheel. This opens the microswitch and de-energizes relay K causing the pump to stop.

Raising the microswitch arm on the rim 61 of wheel 57 connects power directly to the clock motor and causes the clock motor to run continuously to drive the slotted wheel until the microswitch arm drops into another slot 63, shutting off the clock motor and again energizes relay K to start the pump motor and the pump. The cycle then begins again.

In FIGURE 2 the slots on wheel 57 are shown a quadrant apart. Thus if the time required for one revolution of the Wheel at constant operation is 24 hours, the down time of the pump while the wheel is moving between slots is six hours. After the clock is rotated to the next slot the microswitch arm will drop again actuating relay K to turn off the clock motor and energize the pump. The down-time and the number of poundings required to stop the pump are adjustable by changing the wheel configuration.

The sensitivity adjuster 70 can vary the amplitude of the signal fed to the detector 52. It is set at the well, during pounding, at a level high enough so that the peaks of pounding Wavelets will clearly pass the detector 52; but at a level low enough so that the noise between the pounding wavelets will not pass the detector 52. The integrated time adjuster 90 varies the length of the multivibrator output pulse. The repetition rate of the multivibrator pulses is the pump stroke rate, because there is one pounding wavelet per pump stroke cycle, and each pounding wavelet causes one multivibrator pulse. The multivibrator pulse length can be varied from almost zero to almost the pump stroke period. The pulse length determines how long the clock motor will run during each pump stroke period and therefore how many pounds of the pump will occur before the pump is stopped. If it runs, for example, 6 seconds, and if the pump stroke period is 12 seconds, then the clock will be running half the time. If the Width of the slot in the wheel is 3% and the revolution rate at constant running is one revoluti'on per day, minutes will be required for the slotted wheel to turn the 3% to shut off the pump. The pump will therefore be allowed to pound for 30 minutes before shut-down. Adjustment of the shut-down time is made by changing the number of slots on the slotted wheel. For example, a four slotted Wheel gives a six hour shutdown, a two slotted wheel gives a 12 hour shut-down, etc. This, of course, assumes that the slotted wheel cycle is one day and that the slot is 3% in width.

The present invention thus provides for an adjustable period of operation of the pump while it is pounding. Operation for a time during this period is often necessary to insure maximum production from the well. The apparatus of the present invention is so arranged as to provide for adjustable limited operation of the pump while it is pounding. A further advantage of the present invention is that stray vibration will not operate to actuate the control mechanism and abort-ively stop the pump. First the vibration must be above a certain level to actuate the control system and secondly, the vibration must occur during a plurality of pumping cycles to actuate the controller to shut off the pump.

Referring now to FIGURE 3, a circuit diagram for the preferred embodiment of the present invention is shown. A signal sensed by the geophone is transmitted to the amplifier through suitable conductors. A preferred geophone includes a weighted coil which is suspended in a magnetic field by a delicate spring. Vibration of the geophone causes the coil to move up and down in the magnetic field resulting in an induced voltage in the coil. This induced voltage is transmitted from the geophone to the amplifier.

The amplifier uses two stages of silicone transistors 101 and 102 connected in a common emitter configuration with overall negative feedback to insure gain and bias stability. Since the entire amplifier is direct-coupled, bias stability is improved by the negative feedback loop. The negative feedback also improves low frequency response. Transistor 101 operates as a class A common emitter amplifier. Resistor 105 provides emitter bias for this stage but it is by-passed for signal frequency so that the voltage gain of transistor 101 is about 200. Transistor 102 is also connected as a class A amplifier and is direct-coupled to transistor 101. Resistors 100 and 106 provide emitter bias for transistor 102. Resistor 100 is by-passed for signal frequencies but resistor 106 is not. Resistor 106 thus provides degenerative feedback for transistor 102 as well as for transistor 101. The voltage gain of transistor 102 is about 10. The total amplifier gain is about 2000 without feedback and about 200 with feedback. The amplifier gain is adjusted by resistor 107.

The amplifier signal is detected by means of capacitor 108, diode 109 and diode 110. These components are connected in a voltage double circuit. When the output of transistor 102 is driven less positive by the signal, diode 109 conducts and capacitor 108 discharges. When the signal drives the output of transistor 102 more positive, diode 109 is reversed biased and capacitor 108 charges through diode 110 and resistors 111 and 117. The detected signal appears across resistor 111 and is applied to the base of transistor 112.

Transistors 112 and 114 are connected to provide an adjustable integrating time that is used to control the timing motor. The transistors 112 and 114 are connected together in a monostable multivibrator circuit, that is, they have only one stable state. If they are triggered by the detector output, they will flip over to their unstable state, but they will flop back after a short time. This type of circuit is sometimes called a one-shot multivibrator. In the stable state transistor 114 is conducting and transistor 112 is nonconducting. Transistor 114 is held in the conducting state by the current through resistors 115 and 116. Sufiicient current passes through resistors 115 and 116 to saturate transistor 114. The emitter of transistor 112 is at about +1 volt. The base of transistor 112 is held at about +0.6 volt by resistor 117 and resistor 111 and hence transistor 112 is cut off. The

collector of transistor 112 is at about +12 volts and the base of transistor 112 is at about +1.6 volts so that capacitor 118 is charged to .about 10.4 volts. If the detected output raises the base of transistor 112 more positive than its emitter, transistor 112 will start to conduct and its collector voltage will drop. Capacitor 118, however, connects the collector of transistor 112 to the base of transistor 114 so that the base of transistor 114 will go less positive tending to turn transistor 114 oif. The regenerative effect of capacitor 118, resistor 117 and resistor 111 abruptly switches the multivibrator to its unstable state with transistor 112 conducting the transistor 114 nonconducting. Capacitor 118 will now begin to discharge through resistors 115 and 116. When the capacitor 118 has discharged enough to let the base of transistor 114 go positive with respect to its emitter, transistor 114 will start to conduct. The regenerative effect of resistor 117 and resistor 111 will cause the multivibrator to abruptly switch back to its stable state.

The multivibrator will remain in its stable state until it is triggered again by the detector output. The length of time that it stays in the unstable state after being tn'ggered is determined by the time constant of capacitor 113 and resistors 115 and 116. The pounding time prior to shut-down is adjusted by the variable resistor 115 in the multivibrator circuit, that is, the length of time that the multivibrator stays in the unstable state after being triggered is determined by the time constant of capacitor 118 and resistors 115 and 116.

The timing circuit permits the pump to continue running for a predeterminable time after fluid pounding starts to occur. This insures that the pump is not turned off by extraneous noise. This function, as well as the timeclock function is provided by a timing mot-or 120. The timing motor 120 is preferably a one revolution per day timing motor. The timing motor 120 drives a slotted wheel which activates microswitch S Each time that K is de-energized by a pounding impulse, the contacts of K apply 110 v. A.C. power to the motor for a short time. The motor thus moves forward in small increments until finally the slotted wheel lifts the microswitch activator out of the slot. Microswitch S, then de-energizes relay K turning off the pump and at the same time microswitch S applies 110 v. A.C. power to the motor 120. The motor 120 runs continuously until the microswitch actuator drops into the next notch, at which time the motor is turned off; relay K is energized; and the pump started. The pump will now run until fluid pounding occurs. Relay K will again advance the motor in small increments until the microswitch actuator is lifted out of the slot and the pump stops again, The length of time that the pump is turned off is controlled by the time interval between succeeding slots in the timing wheel or cam 57.

The power for the controller is supplied by transformer T which takes 440 v. A.C. on the input and steps it down to 110 v. A.C. to supply power for the motor 121) and the power relay K A half-way rectifier 122 rectifies the 110 v. A.C. to provide DC. power for the transistor circuit. Capacitor 123 filters the rectified DC. and resistor 124 drops it down to 12 volts. Diode 125 is a Zener diode which regulates the 12 volt D.C. and removes any line transients that might be harmful to the transistors.

A neon light 127 is connected in parallel with the motor 120 and thus is caused to light every time the timing motor is energized. The neon light is useful in installing and setting the sensitivity of the controller. Installation of the controller is quite simple. The control box can :be mounted at any convenient distance from the pump, preferably near the motor contactor. 440 v. A.C., 60 c.p.s., single phase, is wired into the power transformer and the normally open contacts of relay K are wired in series with the pump motor contactor. The geophone should be clamped temporarily to the Sampson post. After the installation and adjustments are completed, the geophone can be bolted permanently to its final location on the 6 pumping structure. The geophone is connected to the control box by a two-wire twisted pair cable.

Only two adjustments are required for the unit; sensitivity and pounding time. The sensitivity control is most easily adjusted by observing the neon light. This light is in parallel with the motor and thus lights every time the unit senses pounding. Assuming that the pump is pounding and the sensitivity control is turned to zero, the neon light should remain off. If the sensitivity control is slowly turned up, at some setting the neon lamp will come on at the instant of pounding. It should light only once during a pump cycle. If the sensitivity control is turned up further, the light will come on several times during a pump cycle thus indicating that the unit is being triggered by noise. The sensitivity control should be turned back to about half way between these two positions. The controller is now adjusted to be sensitive enough to detect pounding but not so sensitive to be triggered by extraneous noise.

The pump should then be turned off and the fluid level allowed to be replenished enough so that the pump does not pound. With the pump back running, but not pounding, the neon light should remain off. If it does come on, it indicates that the controller is set at too sensitive a level and is being triggered by extraneous noise. The sensitivity should be decreased until the neon light remains off. The pump is then allowed to run until it starts pounding, at which time the neon light should come on once per cycle. If it is not possible to find a sensitivity setting such that the neon light comes on when pounding and stays off when not pounding, then a different geophone location should be tried until a location is found where the pounding signal is bigger than the background noise.

Although only a preferred embodiment of the invention has been specifically described, the inventive concept is not limited by this embodiment but is meant to include all equivalents embraced by the scope of the claims.

We claim:

1. Apparatus for controlling the operation of an oil Well pump comprising means for sensing abnormal vibrations of the pumping apparatus, means for transmitting the sensed vibrations to equivalent electrical signals, detector means for detecting signals only above a predeterminable magnitude, multivibrator means for producing an electrical pulse of a predeterminable duration in response to each detected signal, said pulse being of the same duration for each detected signal and switching means responsive to a plurality of the electrical pulses for stopping the operation of the pumping apparatus.

2. The apparatus of claim 1 further characterized by means for restarting said well pump after a predeterminable time interval.

3. Apparatus for controlling the operation of a well pump comprising sensing means for sensing abnormal vibrations occurring in well pumping apparatus, said sensing means having means for producing electrical signals equivalent to sensed vibrations, detector means for detecting said electric signals, multivibrator means for producing an electric pulse of a predeterminable duration in response to each detected signal, a timing wheel means, switch means for controlling the operation of the Well pump, said switch means having a switch arm in contact with said timing wheel means, actuating means on said timing wheel for changing the position of said switch arm to open or close said switch means at least once during each revolution of said timing wheel means, motor means for rotating said timing means and relay means for actuating said motor means in response to each electrical pulse produced by said multivibrator means.

4. The apparatus of claim 3 further characterized in that said actuating means is a slot in the peripheral wall of said timing wheel.

5. The apparatus of claim 3 further characterized by means to restart the well pump a predeterminable time after it has been stopped.

'6. The apparatus of claim 3 further characterized in that the detector means has an adjustable threshold.

7. The apparatus of claim 3 further characterized in that light means are connected With said motor means and that said light means lights when said motor means are actuated.

8. A method of controlling a well pump comprising the steps of sensing abnormal vibrations of the pumping apparatus, converting each of the sensed vibrations to an equivalent electrical signal, detecting only the equivalent 10 electrical signals having a magnitude greater than a predetermined threshold, forming an electrical pulse of a predeterminable duration in response to each detected signal and stopping said pumping apparatus in response to a plurality of said electrical pulses.

References Cited by the Examiner UNITED STATES PATENTS Hennernan et a1. 318460 Hubley 10325 Agrew et al. 103--25 Echols 10325 Floyd 318-460 Johnson 10325 Bensema 10325 MARK NEWMAN, Primary Examiner.

SAMUEL LEVINE, Examiner.

15 W. L. FREEH, Assistant Examiner.

Claims (1)

1. APPARATUS FOR CONTROLLING THE OPERATION OF AN OIL WELL PUMP COMPRISING MEANS FOR SENSING ABNORMAL VIBRATIONS OF THE PUMPING APPARATUS, MEANS FOR TRANSMITTING THE SENSED VIBRATIONS TO EQUIVALENT ELECTRICAL SIGNALS, DETECTOR MEANS FOR DETECTING SIGNALS ONLY ABOVE A PREDETERMINABLE MAGNITUDE, MULTIVIBRATOR MEANS FOR PRODUCING AN ELECTRICAL PULSE OF A PREDETERMINABLE DURATION IN RESPONSE TO EACH DETECTED SIGNAL, SAID PULSE BEING OF THE SAME DURATION FOR EACH DETECTED SIGNAL AND SWITCHING MEANS RESPONSIVE TO A PLURALITY OF THE ELECTRICAL PULSES FOR STOPPING THE OPERATION OF THE PUMPING APPARATUS.

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